1. Field of the Invention.
The present invention relates to an article feeding apparatus and in particular to an apparatus which performs successive operations on each article delivered to each of a plurality of operating stations on a non-flexing belt.
2. Prior Art.
U.S. Pat. No. 4,289,231 to Kaminski discloses exemplary problems of prior art endless belts illustrated in FIG. 4a and 4b. As disclosed in the Kaminski reference, the prior art belts are made endless by riveting (FIG. 4b )or welding (FIG. 4a), if metallic, or adhesively securing if non-metallic. In order to provide accurate indexing of the belt as disclosed in FIGS. 4a and 4b, holes 12 are provided along each edge of the belt which mate with corresponding sprocket spikes on a pair of rotational drums. As stated in U.S. Pat. No. 4,289,231, a number of problems occurred with this belt particularly including failure due to metal fatigue. At that time, Kaminski increased the useful service life of the belt by reducing the bending stress and making it of a non-metallic, yet non-stretchable material, while maintaining the indexing means necessary to assure accurate alignment between the endless belt and the rotating drums so that the article placed upon the endless belt would be accurately positioned at each operation station.
In order to overcome the metal fatigue failure of the endless belts of the prior art apparatus, Kaminski employed a non-metallic non-stretchable belt as illustrated in FIGS. 7-11 of U.S. Pat. No. 4,289,231. The endless belt is made of rubber reinforced with steel wires or cables 46 which are embedded in the rubber material of the belt, so as to yield an endless belt which has a non-metallic exterior surface and yet is unstretchable. Additionally, this new improved belt was equipped with indexing means 42 on the lower surface or inside surface of the loop of the endless belt such that the belt could be properly indexed and aligned at each operational station.
FIGS. 8-11 are a modification of the FIG. 7 device. As illustrated therein, the aperture 50 is a stepped aperture comprising an upper portion 52 and a lower portion 54 so as to form an annular shoulder 56 between the upper and lower portions. The stepped aperture is required to transport a can end, such as illustrated by the reference numeral 48, in order to easily perform certain desired operations at specific operation stations.
During operation of the article feeding apparatus, the articles placed upon the belt, such as the can ends, do not leave the belt apertures. When an operation station includes a lower tool which performs various operations on the article, the belt is flexed downward to place the article on the lower tool. After the operation is completed, the belt is lifted by spring loaded rails such that the article can be transferred without "stumbling" over the lower tool. This procedure works extremely well when the distance of displacement of the belt is kept to a minimum of about 1/4-inch.
If the operation to be performed on the article requires substantially more deflection of the belt, the useful life of the belt is greatly reduced and often results in a broken belt if deflection is too great. Additionally, operations are sometimes required at the extreme outer edges of the article and these operations cannot be accomplished by the stepped aperture belts illustrated in FIGS. 7-11 of U.S. Pat. No. 4,289,231 because the thickness of the belt is greatly reduced in order to obtain a stepped aperture. In other words, the lower portion 54, as illustrated in FIG. 10 of the above-mentioned patent, is sufficiently thin that most operations required at the extreme outer edges of the article cannot be accomplished on the endless belt because the belt cannot support the forces placed on its lower portion. Consequently, the belt frequently breaks if such operations are attempted.
Accordingly, a need exists for an endless belt which has an extended useful service life over that of the prior art devices and includes a method of permitting the belt to be displaced significantly more than the traditional 1/4-inch. Also, the need exists for an endless belt which is sufficiently strong to permit operations to be performed on the article at the extreme edges of the article without cracking or breaking the belt.